The Treasury Department said the action would bar those companies and individuals from doing business with US firms or citizens, and freeze any assets they have in the United States.
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Foreign banks that handle transactions for the companies and individuals could also lose their access to the US banking system under the US sanctions regime.
"The US will target those involved in Iran's illicit enrichment activities. The entire world has made it clear that these activities are unacceptable," Treasury Undersecretary David Cohen said in a statement.
The United States has said Tehran's nuclear program is aimed at acquiring atomic weapons, a charge Iran has repeatedly denied.
The Treasury said the newly announced sanctions were aimed at targeting the international procurement operations of the Atomic Energy Organization of Iran, the Iran Centrifuge Technology Company and Iran's uranium enrichment program.
The individuals targeted by the sanctions were Fereidoun Abbasi-Davani, Seyed Jaber Safdari, Morteza Ahmadali Behzad, Amir Hossein Rahimyar and Mohammad Reza Rezvanianzadeh.
The companies sanctioned were Pouya Control, Iran Pooya, Aria Nikan Marine Industry, Faratech, Neda Industrial Group, Tarh O Palayesh and Towlid Abzar Boreshi Iran.